Field of the Invention
Embodiments of the present invention generally relate to a current feedback technique for capacitive sensing with an input device.
Description of the Related Art
Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems, such as touchpads integrated in, or peripheral to, notebook or desktop computers. Proximity sensor devices are also often used in smaller computing systems, such as touch screens integrated in cellular phones or tablet computers.
Proximity sensor devices may include one or more types of electrodes that are configured for transmitting and/or receiving input sensing signals. The electrodes may be coupled to a processing system that determines various characteristics of acquired input sensing signals in order to detect the presence and/or location of an input object. Processing input sensing signals received via the electrodes generally requires large components, such as a number of large capacitors and/or resistors. For example, receiver components may be coupled to each individual electrode (or to each set of electrodes), requiring tens or hundreds of relatively large capacitors and/or resistors to be included in the proximity sensor device. In addition, as the feature size of proximity sensor devices is decreased, the number of receiver components generally must be increased, further increasing the size of the proximity sensor device.
Accordingly, there is a need for reducing the size of components used to perform input sensing in proximity sensor devices.